Centrifugal separation



W. MAUSS.

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luv-@7230? W. Manuss By Patented Oct. 12, 1920.

UNITED STATES" PATENT OFFICE.

CENTBIEUIGA'IL sEr-ARATIon.

Application filedbctober 31, 1918. Serial n 2eo,597.

To all whom it mag concern:

Be it known that I, IVILHELM MAUss, a British subject, of 72 Cullinan Buildings, Main and Simmonds streets, Johannesburg, Transvaal Province of the Union of South Africa, have invented certain new and useful Improvements in Centrifugal Separa= tion, of which the following is a specification.

The present invention relates to the separation of solids from liquids. Centrifugal separators are known in'which' the drumis formed of conical or similar sections which can be parted to discharge the solid matter. One of said sections is provided with a filter surface transverse to the axis of rotation and in the process of separation the solid matter progressively deposits from the outer part of the drum inwardly while the liquid segregates as an inner layer which passes off through the filter surface'.

The purpose of the present invention is to maintain the filter cloth freely permeable to the liquid, independentlyof the nature of the mixture treated. The invention is thus of special applicability to the treatmentof slimy materials which are diflicultly filterable and are commonly treated by decantation and filter pressing, and also of mixtures which are for all practical purposes unfilterable; a particular application of the invention being the treatment of sugar juice direct from the cane mill, thus avoiding the loss by inversion which occurs in the usual slow gravity decantation step.

The inventionfis illustrated in the accompanying drawings in which- Figure I shows acentrifugal drum. partly in section. 4

Fig. II shows the same with the drum sections separated.

Fig. III is a detail plan of Fi I.

The drawings show a centrifiigal drum consisting of the separable sections 1 and 2. 1 is a hollow cone secured to a hollow shaft 3'. It is'formed with a central aperture 4 to admit the feed pipe 5, and to permit the escape of unseparated material if the drum is ovcrfed. Theother section of the drum consists of a plate 2 adapted to inclose the larger end of the cone and to form with it a separating chamber 6. Said plate is fast to a shaft 7 which passes through the hollow shaft 3, and the drum as a whole is rotated by appropriate means.

Stretched upon the plate 2 and forming one boundary of' the separating chamber 6 is a filter cloth"8 or other material pervious only tog-the liquid constituent of the material under treatment. This cloth is arranged horizontally or approximatelygso, so that adhesive. material readily slips from i it Specification of Letters Patent. -Patented Oct.

under centrifugal force, whil'esuch force 112118 littleten-dency tolift the-cloth from the pate. Beneath the cloth the surface 9Y' f the plate is co'rrugated'and provided "witlrpasQ sages 10 for conveying liquidf Thesep'a'ssages open into a chamber ll 'froi'n which lead radial passages 12, tl1e' outer f'cn'dsof which are turned back'in approximately 2 form at 13 before emerging 'at the'iedge of the plate. Thisrecurved orZJshaped port on of the channel forms a trapQin which iquid is collected to form a comp l'eteoi' partial seal for.the purpose indicated be Undue gyration of the drum'is'p'revented by spring arms- 14 connected to aring: '15 wlthin which the shaft 7 is rotatable.

16 is a receiver for liquidfeftluent and 17 a receiver for the solid,materialjwhich is a left in .the drum fter the'separation is completed.

During the separation period" the drum is positioned with its liquid ettluent'orifices 12 opposite the receiver 16 as shown in Fig. I. hen the discharge of .theli uid is completed the dr um is lowered bodi y and the sections 1 and 2 are parted asindicated in Fig. II so discharging the solid into the receiver 17. The drum is thereafter raised and closed and separation is resumed. .Suitable mechanism for effecting, these movements of the drum is described in detail in application for Letters Patent No. 14,785 of 1917, and need not be referred to here.

The discharge end of the'feed pipe 5 is arranged close to the inner surface of the cone 1, tangentially to the drum and in' the same direction as the rotation of the drum as shown in Fig. III.

Vithin the drum and beneath the feed pipe 5 is arranged a circular baftie 18 which prevents material dropping from the feed pipe directly onto the filter cloth8.

19 is a valve casing carrying a piston valve 20 which is forced upwardly by a spring 21. The valve is provided at the top with a rotatable nozzle 22 which can seat in and revolve with a seating 23 in the lower end of shaft 7. 2is av pipe supplying steam, air orwater under pressureto the chamber 25 within the valve casing; which chamber is closed by the valve 20 when the latter is raised as in Fig. I. \Vhen' the drum 1, 2 descends the shaft 7 seats. on

the nozzle 22 and forces down the valve, so

separating chamber Gwithout passing over the filter cloth 8.

The material is fed at such a limited rate that by the time ithas reached the outer unoccupied part of the separating chambenit has become separated and the solid deposits itself atoms on the walls of the chamber 6' or on the deposit 28 already formed, leav-.

ing the liquid as a radially inward stratum 29. This liquid being in contact with the clean filter cloth 8 passes throughthe same and is discharged through the passages 10 and 12.

The unseparated material is fed continuously at this rate, the solid material constantly accumulating in the outer part of the-chamber and the clear liquid zone being constantly advanced inwardly so that the liquid passes throughsuccessive clean sections of the filter cloth, which are afterward covered by the solid deposit. 1

As soon as the filter cloth is substantially covered with deposit, feeding is stopped; any excess material fed in being discharged I from the opening 4 which is of slightly under pressure is passed from the supply greater radius than the inner edge of the filter cloth. The drum 1, 2, is then lowered and opened and the accumulated solid thereby discharged into the receiver 17.

As the drum descends and opens, fluid 24 into the chamber 11 and is blown through the filter cloth 8 from the underside, so cleaning the same. The partial or complete stoppage of the traps 13 by liquid held therein by centrifugal force, or even the limited size of the passages themselves,

causes sufficient fluid pressure to be maintained in the chamber 11 to enable the cloth to be effectively blown through. Steam is used for the purpose in preference to other fluids to avoid drying the filter cloth. Subsequently the drum is raised and closed and feeding is resumed.

I claimi 1 .A process of centrifugal separation of solids and liquids, which consists in progressively depositing mixed solids and fluids near the circumference of the interior of a centrifugal drum having a filtering surface, revolving said drum to cause the solids to progressively advance on to the filtering surface while the liquids drain through the filtering surface, and preventing unseparated materlal from coming into contact with the filter surface.

2. In the process as claimed in claim 1, the step ,which consists in feeding the mixture at a limiting rate on to a wall of the drum remote. from the filter surface, where. by separation is substantially completed before the constituents reach the filter surface.

.3- In the process as claimed in claim 1, the step which consists in periodically passing fluid inwardly through the filter surface to clean the same.

4. In the process as claimed in claim 1,

the steps which consist in feeding the mix ture at a limited rate on to a wall of the drum remote from the filter surface, and periodically passing fluid inwardly through the filtgrsrurfaceto clean the same.

5. A ce trifugal separator comprising a drum having an inner conical surface and a filter surface arranged perpendicular to the axis of, the conical surface, a separating chamber inclosed by said surfaces, and feeding means arranged to feed exclusively onto said conical surface. a

6. Apparatus as claimed in claim 5, in which the mixture is fed tangentially in the direction of rotation of the drum.

7. In acentrifugal separator as claimed in claim 5, a baffie arranged between the feeding means and the filter surface to prevent feed material from directly reaching the latter.

' 8. Ina centrifugal separator comprising a drum provided .With' a filter surface arranged for liquid normally to pass outwardly through it, means for producing an inward flow of cleaning fluid through the filter surface to clean the same.

9. A centrifugal separator as claimed in claim 8, in which a trap outlet for liquid is arranged beneath the filter surface to enable fluid pressure to be set up beneath the filter surface.

10. A separator as claimed in claim 8 in which'the drum is movable bodily, and in which such bodily movement of the drum causes the admission of pressure fluid beneath the filter surface.

11. In a centrifugal separator, a drum provided with a filter surface substantially transverse to the axis of rotation, and said drum being formed with a central open-- ing of somewhat greater radius than the inner boundary of the filter surface.

12. A centrifugal separator comprising a having their bases abutting, a filter surface arranged in the drum substantially transverse to the axis of rotation,'and dividing the interior of the drum into a plurality of chambers, means for feeding the material to be separated on to the inner surface of one of the cones, and a fluid outlet provided in the other cone.

13. A separator of the kind defined in claim 12, in which the cones are relatively movable axially.

14. A separator of the kind defined in claim 12 having means for admitting cleaning fluid to the interior of the cone having the fluid outlet.

15. The process of centrifugal separation which consists in progressively depositing the solid constituent of a mixture in the outer part of a centrifugal drum having a filtering surface disposed materially normally to the axis of rotation of the drum, and causing the liquid to be segregated as an inner layer which passes through the filter surface while preventing unseparated material from coming into contact with the filter surface.

16. In a centrifugal separator, a drum havinga conical surface and a filter surface forming between them an outwardly tapered chamber and feeding means arranged to feed exclusively onto said conical surface;

In testimony whereof I afiix my signature.

WILHELM MAUSS. 

